Metal-organic frameworks (MOFs) have emerged as an important class of hybrid organic-inorganic materials. One of the reasons they have gained remarkable attention is attributed to the possibility of altering them by postsynthetic modification, thereby providing access to new and novel advanced materials. MOFs have been applied in catalysis, gas storage, gas separation, chemical sensing, and drug delivery. However, their bactericidal use has rarely been explored. Herein, we developed a two-step process for the synthesis of zirconium-based MOFs metalated with silver cations as a potent antibacterial agent. The obtained products were thoroughly characterized by powder X-ray diffraction, scanning electron microscopy, UV-visible, IR, thermogravimetric, and Brunauer-Emmett-Teller analyses. Their potency was evaluated against E. coli with a reported minimal inhibitory concentration and minimal bactericidal concentration of as low as 6.5 μg/mL of silver content. Besides the novelty of the system, the advantage of this strategy is that the MOFs could be potentially regenerated and remetalated after each antibacterial test, unlike previously reported frameworks, which involved the destruction of the framework.

It is generally accepted that positively charged molecules are the gold standard to by-pass the negatively charged cell membrane. Here, it is shown that cellular uptake is also possible for polymers with negatively charged side chains and hydrophobic backbones. Specifically, poly[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene], a conjugated polyelectrolyte with sulfonate, as water-soluble functional groups, is shown to accumulate in the intracellular region. When the polymer hydrophobic backbone is dissolved using polyvinylpyrrolidone, an amphiphilic macromolecule, the cellular uptake is dramatically reduced. The report sheds light on the fine balance between negatively charged side groups and the hydrophobicity of polymers to either enhance or reduce cellular uptake. As a result, these findings will have important ramifications on the future design of targeted cellular delivery nanocarriers for imaging and therapeutic applications.